Asymptomatic carriage of Cryptococcus neoformans in the nasal cavity of the koala (Phascolarctos cinereus)

Abstract

Over a 22‐month period, sequential nasal and skin swabs were obtained from 52 healthy captive koalas (Phascolarctos cinereus) from the Sydney region. Cryptococcus neoformans was isolated in 17 koalas from 64 of 262 (24%) nasal swabs and from nine of 262 (3%) skin swabs. Prevalence of nasal colonization varied seasonally from 12% (3/25) to 38% (10/26). Cryptococcus neoformans var. gattii alone was cultured from 37, var. neoformans alone from 22 and both varieties from five nasal swabs. Of 33 koalas sampled on three or more occasions, organisms were isolated persistently from six, occasionally from eight and never from 19. Two koalas were persistently and heavily (≥100 colonies/plate) colonized by C. neoformans var. gattii and two with var. neoformans. Isolation of C. neoformans var. gattii from the skin was low grade and sporadic. No koalas from which C. neoformans was persistently isolated showed clinical signs of cryptococcosis and all except one had a negative latex cryptococcal antigen test, therefore the nasal cavity was presumed to be colonized by, rather than infected with, C. neoformans. Preliminary observations of koalas from Coffs Harbour indicated a much higher prevalence of colonization by C. neoformans, suggesting that environmental factors influenced the extent of carriage by C. neoformans.

Cryptococcosis in Gilbert's and Long-Nosed Potoroo

“…1,8,10 Cases of cryptococcosis in quokkas (Setonix brachyurus), wallabies (species unspecified), and numbats (Myrmecobius fasciatus) were found in the archives of the Western Australian Department of Agriculture and Food Animal Health Laboratory, and cases of cryptococcosis in quokkas, a red-necked wallaby (Macropus rufogriseus banksianus), a dusky antechinus (Antechinus swainsonii), and a feathertail glider (Acrobates pygmaeus) were found in the files of the Registry of Wildlife Pathology at Taronga Park Zoo (Rose, pers. comm.).…”

Cryptococcus gattii in Wildlife of Vancouver Island, British Columbia, Canada

“…Asymptomatic carriage of C. gattii has been recognized in companion-animal species of British Columbia, presumably as a result of contact with airborne infectious material (Bartlett, 2003;Duncan et al, 2005). Environmental exposure and asymptomatic colonization of the respiratory tract has been proposed to be much more common than clinical disease (Malik et al, 1997;Connolly et al, 1999); however, variables influencing the initiation of infection remain unclear. The prevalence of the organism in other British Columbia wildlife is unknown.…”

“…Cryptococcus gattii has been repeatedly isolated from the nasal cavity of living wild and domestic animals; however, there are conflicting results concerning the agreement between deep and superficial nasal swabs (Duncan et al, 2005;Connolly et al, 1999). Standardization of sampling techniques is important in cross-species studies; given the lack of data for agreement between the sampling techniques in wild mammals, it should be noted that samples collected from living animals differed from those samples collected postmortem.…”

Screening of antigenemia and isolation of Cryptococcus neoformans and C. gattii from cloaca and crop of birds in the state of Paraná, Brazil

“…do not invade the birds'organism, consequently discarding possible subclinical infections and the status of carrier. Negative results were also obtained for the antigenemia of dogs, cats, and koalas with nasal cavity colonization by C. neoformans demonstrating a low invasive capability of the fungus in immunocompetent animals (Malik et al 1997, Connolly et al 1999. The only animal with positive antigenemia had a low title.…”

“…rarely cause clinical diseases in birds, because yeast cannot either grow at the bird's temperature or survive its passage through the intestinal tract, beyond its low invasive capability in birds (Mitchell & Perfect 1995, Casadevall & Perfect 1998, Filiú et al 2002. Clinical infections with a subsequent elimination of the yeast from the body by intact cell immunity can also occur (Connolly et al 1999) and, in this case, birds can be transitory carriers of the disease (Bauwens et al 1986, Mitchell & Perfect 1995. In humans, clinical diseases are uncommon, but contact and sensitivization to antigens are more prevalent with antibodies detected in 20% of the adult population (Mitchell & Perfect 1995, Malik 2003.…”